Abstract

The principle, fabrication and characterization of a dielectric MEMS cantilever located a few 100 nm above a racetrack ring resonator are presented. After fabrication of the resonators on silicon-on-insulator (SOI) wafers in a foundry process, the cantilevers were integrated by surface micromachining techniques. Off-state deflections of the cantilevers have been optimized to appropriately position them near the evanescent field of the resonator. Using electrostatic actuation, moving the cantilevers into this evanescent field, the propagation properties of the ring waveguide are modulated. We demonstrate 122 pm tuning of the resonance wavelength of the optical ring resonator (in the optical C-band) without change of the optical quality factor, on application of 9 V to a 40 µm long cantilever. This compact integrated device can be used for tuning/switching a specific wavelength, with very little energy for operation and negligible cross talk with surrounding devices.

(A) Static deflection of a 40 µm long cantilever at the off-state (0 V) and at pull-in (9.2 V), measured by WLIM. And (B) OM image of the integrated device which was measured, where the rectangular square represents the WLI scanning area.

SEM images showing (A) the ring resonator and access waveguides collapsed by overetching of the SL and PL layer during the RIE of the SiNx cantilever layer and (B) stringer type B distributed all over the wafer.